#include<stdio.h>


int main()      //第50个月多少兔子
{
    long a[50]={0};  //1 1 2 3 5 8 13
    a[0] =1;
    a[1] =2;
 
    for (int i = 2; i <50 ; i++)
    {
        a[i] = a[i-1] + [i-2];
    }
    printf("%ld\n",a[49]);   
    return 0;
}



